Bypass

Bypass is water that reaches your cup without doing much extraction work. In a cone like a V60, water poured high on the wall can run down the paper and through the gap between the bed and the filter, skipping most of the coffee. In espresso and immersion brews, the same idea shows up as channeling, where water races through a low-resistance path.

Why it matters: bypass water is nearly plain water by the time it lands in the cup. It lowers strength and total dissolved solids (see tds) without changing how much you actually pulled from the grounds. So a brew can be both weak and unbalanced: the coffee that did contact water may be fine, but the diluting bypass thins the whole thing.

A little bypass is unavoidable and even useful: some recipes pour deliberately onto the bed center to control extraction while a controlled amount of bypass softens an over-extracted, bitter brew. The skill is keeping it intentional. Pour toward the center, keep the slurry level, and avoid blasting the filter walls.